Electromagnetic valve

ABSTRACT

In an electromagnetic valve, a stator assembly includes an electrically energizable coil and a thin-walled core which receives and reciprocally supports an armature. The thin-walled core has a closed end and an open end, the open end being in fluid communication with a fluid flow passage within a valve member. The valve member reciprocates with the armature to control flow rate in the flow passage. A flange integral with the thin-walled core extends about the open end. A washer receives the thin-walled core and abuts the flange. The flange and the washer are received in a recess in the valve body and are permanently and sealingly fixed therein by a swaged joint in the valve body.

TECHNICAL FIELD

The present invention relates to an electromagnetic valve apparatus thatgenerates a magnetic attractive force between a stationary field coiland an armature for controlling a flow rate in a flow passage by meansof a valve member which is displaced by the armature.

BACKGROUND OF THE INVENTION

Generally, it is known that an electromagnetic valve has a field coilfixed within a housing portion and an internal armature that canreciprocate, being attracted by the field coil in one of thereciprocating directions. A valve body is mounted to the housing portionand defines a flow passage, with a valve member mounted to the armaturefor cooperating with the valve body to control flow through the flowpassage.

In valves of this type the mechanical connection between the housingportion and valve body should avoid the possibility that the axes of thehousing and valve body portions may deviate from each other due toassembly errors or other reasons and should provide a fluid tight seal.Moreover, in designs where the armature is exposed to fluid pressure, aseparating wall is required about the armature to contain the fluid fromentering the field coil. In such valves there is therefore a need forthis separating wall to be thin so as to mitigate any loss of magneticattractive force. It is an object of the present invention to addressthe above needs or more generally to provide an improved electromagneticvalve.

SUMMARY OF THE INVENTION

According to one aspect of the present invention, there is provided anelectromagnetic valve comprising:

-   -   a stator assembly including an electrically energizable coil;    -   an armature cooperating with the stator assembly to define a        magnetic circuit upon energization of the coil;    -   wherein the stator assembly includes a thin-walled core which        receives and reciprocally supports the armature, the thin-walled        core having a closed end and an open end;    -   an annular flange integral with the thin-walled core and        extending about the open end;    -   a valve body defining a flow passage between ports in the valve        body;    -   a recess in the valve body in which the flange is received, such        that the open end is in communication with the flow passage;    -   a washer receiving the thin-walled core therethrough and        abutting the flange;    -   a swaged joint in the valve body sealingly fixing the flange and        washer in the recess; and    -   a valve member mounted to the armature such that the valve        member reciprocates with the armature to control a flow rate in        the flow passage.

Preferably, the washer and valve body are made of materials that arerelatively softer than the material of the thin-walled core.

Preferably, the thin-walled core is cylindrical and the closed end isclosed by a plug member having an inner portion and an outer portion.The inner portion is received in the thin-walled core. The inner portionhas an inner face defining the closed end and a peripheral facecomplementary to the thin-walled core, with first and second annularrecesses formed in the peripheral face. A sealing ring is received inthe first annular recess, and a protrusion from the thin-walled coreextends into the second annular recess for fixing the plug member in thethin-walled core.

Preferably, the valve body defines a valve seat extending about arestricted portion of the flow passage. The valve member includes acompliant seal for engaging the valve seat. The valve further includes acompression spring having one end abutting the inner face for urging theseal to engage the valve seat.

It is preferred that the washer has an edge about which the swaged jointis formed, the edge being pressed round during formation of the swagedjoint.

In another aspect, the invention provides an electromagnetic valvecomprising:

-   -   a stator assembly including an electrically energizable coil        encapsulated in a prismatic polymeric body;    -   an elongate aperture extending through the body and the coil;    -   an armature cooperating with the stator assembly to define a        magnetic circuit upon energization of the coil;    -   wherein the stator assembly further includes a thin-walled core        which receives and reciprocally supports the armature, the        thin-walled core received in the elongate aperture and having        longitudinally opposing first and second ends, the first end        being disposed within the body and the second end disposed        outside the body;    -   a plug member received in and closing the first end, the plug        member having an inner face,    -   an annular flange integral with the thin-walled core and        extending about second end;    -   a valve body defining a flow passage between ports in the valve        body and a valve seat extending about a restricted portion of        the flow passage;    -   a recess in the valve body in which the flange is received, such        that the second end is in communication with the flow passage;    -   a washer receiving the thin-walled core therethrough and        abutting the flange;    -   a swaged joint in the valve body sealingly fixing the flange and        washer in the recess;    -   a compliant valve member mounted to the armature; and    -   a compression spring having opposing ends abutting the inner        face and valve member for urging the valve member to engage the        valve seat such that the valve member reciprocates with the        armature to control a flow rate in the flow passage.

This invention provides an electromagnetic valve which is effective andefficient in operational use, and which by its overall simple designminimizes manufacturing costs. It allows a thin-walled core to be usedwhich requires a minimum of material.

BRIEF DESCRIPTION OF THE DRAWINGS

Preferred forms of the present invention will now be described by way ofexample with reference to the accompanying drawings, in which:

FIG. 1 is a sectional view of an electromagnetic valve according to apreferred embodiment of the invention;

FIG. 2 is an exploded pictorial view of the valve of FIG. 1;

FIG. 3 a is a schematic cross section illustrating the assembly of thecore and valve body of the valve of FIG. 1 before the formation of aswaged joint, and

FIG. 3 b is a schematic cross section showing the assembly of FIG. 3 bafter the formation of a swaged joint.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring to FIGS. 1 and 2, an electromagnetic valve 10 generallyincludes a stator assembly 11, an armature 12 and a valve body 13. Thestator assembly 11 includes a polymeric body 14 of a rectangularprismatic form with an opening 15 with a circular section that extendstherethrough. The body 14 is moulded polymer and encapsulates a fieldcoil 16 wound on a bobbin 20. The bobbin 20 includes a thin cylindricalwall 19 generally aligned with the opening 15 with annular lips 17, 18at axially opposing ends of the wall 19. The coil 16 is thus boundedbetween the cylindrical wall 19, lips 17, 18 and the body 14. Electricalcontacts 21 project from the body 14 and are electrically coupled to thecoil 16.

As used herein, the term “axial” refers to a direction substantiallyparallel to the axis 60. The term “radial” refers to a directionsubstantially orthogonal to the axis 60. The term “circumferential”refers to the direction of a circular arc having a radius substantiallyorthogonal to the axis 60.

The stator 11 is an assembly that further includes a core 22 formed asby deep drawing from stainless steel. The core 22 includes a thin-walledtubular portion 23 with an integral annular flange 24 formed at a first,open end 32 thereof and protruding orthogonally to the tubular portion23. The flanged core 22 may be of stainless steel, brass or any othersuitable non-magnetic metal materials, usually made by a drawing processand then cutting out as an integral piece.

The valve body 13 is formed from brass and defines a flow passage 25between inlet and outlet ports 26, 27 having internal screw threads (notshown). The valve body 13 defines a valve seat 55 extending about arestricted portion 56 of the flow passage 25

A recess 28 in one side of the valve body 13 opens into the flow passage25 and is bounded by a lip 29. The core 22 is received in a washer 30.The washer 30 is preferably metallic and of a material which is softerthan the material of the core 22, such as annealed aluminium. The washer30 abuts the flange 24. A swaged joint 31 formed by deformation of thelip 29 (from its original form indicated by 29′ in FIGS. 2 and 3 a)fixes the flange 24 and washer 30 in the recess 29. In this manner theopen end 32 of the core 22 is fixed in communication with the flowpassage 25, while aligned with the valve seat 55.

Opposing the open end 32 the core has a closed end 33 closed by a plugmember 34 having an inner portion 35 and an outer portion 36. The innerportion 35 is received in the core 22 and has a flat inner face 37 whichextends radially to define the closed end 33. A peripheral face 38 iscomplementary to the core 22 and includes first and second annularrecesses 39, 40 therein. A sealing ring 41 is received in the firstannular recess 39 and an inwardly protruding annular rib 42 is receivedin the second annular recess 40 for fixing the plug member 34 in thethin-walled core 22. A shading ring 43 is embedded into the face 37. Theouter end 36 includes a shoulder 44 for abutting the end face 45 of thecore 22 and a circumferential groove 46.

FIGS. 3 a and 3 b illustrate the manner in which the core 22 and valvebody 13 are permanently joined by the swaged joint 31 (note that thearmature 12 enclosed therein has been omitted from these two drawingsfor clarity). The valve body 13 is manufactured such that an annular,radially-aligned face 48 extends in and about the recess 28. The lip 29extends axially and has a cylindrical, axially aligned inner face 47.The washer 30 has inner and outer cylindrical faces 49 and 50 whichmatch with, and are a snug fit with, adjacent cylindrical outer face ofthe core 22 and cylindrical face 47 of the recess 28 respectively. Thisarrangement, and in particular the snug fit, allows the core end 32 andwasher 30 thereon to enter the recess 28 in a guided manner and thenholds the core 22 in axial alignment with and stable location about therecess 28, thereby facilitating subsequent manufacturing processincluding in particular the forming of the swaged joint 31.

Opposing principal faces 51, 52 of the washer are flat and co-parallel,with the inner face 51 abutting the core flange 24, which in turn abutsthe annular face 48 in the recess 28. In a swaging operation, a presstool (not shown) plastically deforms the lip 29 to engage the outerwasher face 52 thereby forming a tight swaged joint 31. Upon closing inon the washer 30, the lip 29 presses against and thus squashes anddeforms the washer 30 especially about its upper rim between the outerfaces 50 and 52 (see FIG. 3 b), thereby ensuring a fluid-tight jointbetween the lip 29 and the washer 30 with the core 22. The upper rim wasoriginally a right-angled edge and is now pressed round. The material ofthe washer 30 is preferably slightly softer than that of the lip 29 fordeformation.

The valve body 13 and core sub-assembly of FIG. 3 b (including thearmature 12) is assembled to the body 14 by inserting the core 22 frombelow into the opening 15. A washer 65 is received in a top recess 61 inthe body 14, and they are retained on the core 22 by a spring clip 62which engages the groove 46 at the exposed end of the plug member 34.

The armature 12 has a cylindrical surface 56 complementary to the innersurface of the core 22 and an axially extending recess 57. The armature12 may be made from a ferromagnetic material. Held within the armature12 is a valve member in the form of a compliant seal 59 for engaging thevalve seat 55. The valve further includes a compression spring 58received in the recess 57 having one end abutting the inner face 37 andanother end abutting the seal 59 for urging it to engage the valve seat55. In this manner the seal 59 is mounted to the armature 12 such thatthe seal 59 reciprocates with the armature 12 to control the flow ratein the flow passage 25. When the coil 16 is energized the armature 12 isattracted by the coil 16, thereby separating the seal 59 from the valveseat 55 to open the valve (as shown in FIG. 1).

Aspects of the present invention have been described by way of exampleonly and it should be appreciated that modifications and additions maybe made thereto without departing from the scope thereof.

1. An electromagnetic valve comprising: a stator assembly including anelectrically energizable coil; an armature cooperating with the statorassembly to define a magnetic circuit upon energization of the coil,wherein the stator assembly includes a cylindrical thin-walled corewhich receives and reciprocally supports the armature, and thethin-walled core has a closed end and an open end, and an integralannular flange extending around the open end; a plug member closing theclosed end of the thin-walled core, wherein the plug member has an innerportion and an outer portion, the inner portion is received in thethin-walled core, and the inner portion includes an inner face definingthe closed end, and a peripheral face, complementary to the thin-walledcore, the peripheral face including first and second annular recesses; asealing ring received in the first annular recess, wherein a protrusionfrom the thin-walled core extends into the second annular recess andfixes the plug member in the thin-walled core; a valve body defining aflow passage between ports in the valve body; a recess in the valve bodyin which the annular flange of the thin-walled core is received, withthe open end in communication with the flow passage; a washer, throughwhich the thin-walled core passes, abutting the annular flange of thethin-walled core, wherein the washer has inner and outer cylindricalfaces that match with respective adjacent cylindrical faces of thethin-walled core and the recess in a snug fit which holds thethin-walled core in axial alignment with the recess; a swaged joint inthe valve body sealingly fixing the annular flange of the thin-walledcore and the washer in the recess; and a valve member mounted on thearmature, wherein the valve member reciprocates with the armature tocontrol flow in the flow passage.
 2. The electromagnetic valve of claim1, wherein the washer and the valve body are softer than the thethin-walled core.
 3. The electromagnetic valve of claim 1, wherein thevalve body defines a valve seat extending about a restricted portion ofthe flow passage, the valve member includes a compliant seal forengaging the valve seat, and the valve includes a compression springhaving an end abutting the inner face and urging the seal to engage thevalve seat.
 4. The electromagnetic valve of claim 1, wherein the washerhas an edge about which the swaged joint is located, the edge is, in thecross section, rounded in the swaged joint.
 5. An electromagnetic valvecomprising: a stator assembly including an electrically energizable coilencapsulated in a prismatic polymeric body; an elongate apertureextending through the body and the coil; an armature cooperating withthe stator assembly to define a magnetic circuit upon energization ofthe coil, wherein the stator assembly includes a thin-walled cylindricalcore which receives and reciprocally supports the armature, and thethin-walled core is received in the elongate aperture, and haslongitudinally opposing first and second ends, the first end beingdisposed within the body and the second end being disposed outside thebody, and an integral annular flange extending around the second end; aplug member received in and closing the first end of the thin-walledcore, the plug member having an inner face, a peripheral face, theperipheral face being complementary to the thin-walled core andincluding first and second annular recesses; and a sealing ring receivedin the first annular recess, wherein a protrusion from the thin-walledcore extends into the second annular recess and fixes the plug member inthe thin-walled core: a valve body defining a flow passage between portsin the valve body and a valve seat extending about a restricted portionof the flow passage; a recess in the valve body in which the annularflange of the thin-walled core is received, such that the second end ofthe thin walled core is in communication with the flow passage; awasher, through which the thin-walled core passes, abutting the flange;a swaged joint in the valve body sealingly fixing the annular flange ofthe thin-walled core and the washer in the recess; a compliant valvemember mounted on the armature; and a compression spring having opposingends abutting the inner face and the valve member, respectively, andurging the valve member to engage the valve seat, wherein the valvemember reciprocates with the armature to control flow in the flowpassage.
 6. The electromagnetic valve of claim 5, wherein the washer andthe valve body are softer than the thin-walled core.
 7. Theelectromagnetic valve of claim 5, wherein the washer has inner and outercylindrical faces that match with respective adjacent cylindrical facesof the core and the recess in a snug fit which holds the core in axialalignment with the recess.
 8. The electromagnetic valve of claim 6,wherein the washer has an edge about which the swaged joint is located,the edge is, in cross section, rounded in the swaged joint.